The vast majority of used nuclear fuel produced by U.S. reactors since the dawn of commercial nuclear energy five decades ago is presently stored in fuel pools. In the past fifteen years, utilities have been moving used nuclear fuel to the so-called “dry storage” systems which are so named because the used nuclear fuel is stored in an extremely dry state surrounded by an gas, such as helium, to prevent degenerative oxidation. Dry storage of used nuclear fuel in casks acquitted itself extremely well during the Fukushima Daiichi cataclysm when the double-event of a Richter scale 9.0 earthquake followed by a 13.1+ meter high tsunami failed to cause a single cask at the site to leak. The fuel pools, on the other hand, suffered loss of cooling and structural damage. The Fukushima experience has undoubtedly given solid credentials to dry storage as a reliably safe means to store used nuclear fuel. Even before Fukushima, the security concerns in the wake of 9/11 had given a strong impetus in the United States to reduce the quantity of used nuclear fuel stored in the water-filled pools by moving it into dry storage. At present, a large number of canisters containing tons of used nuclear fuel are stored on-site at commercial storage facilities in the United States. Over 200 canisters are being added to the dry storage stockpile in the United States each year. On-site storage is also gaining wider acceptance in Europe and Japan.
At present, virtually every nuclear plant site has its own on-site storage facility, commonly referred to as an Independent Spent Fuel Storage Installation (“ISFSI”). ISFSI loaded with free-standing above-grade casks is an unmistakable presence in the plant's landscape that raises “optical” problems of community acceptance even though the dry storage casks are among the most tenor-resistant structures at any industrial plant. Even so, the perceived risk of a 9/11 type assault adds to the sense of unease that has been scarcely ameliorated by a not well publicized scientific finding by the experts at a U.S. national laboratory which holds that the casks in use at the U.S. plants are capable of withstanding the impact from a crashing aircraft without allowing any radioactive Matter to be released into the environment. The superb structural characteristics of the dry storage systems have likely played a role in the Presidential Blue Ribbon Commission's recent report that calls for Interim Storage of spent fuel in dry storage casks at a limited number of sites where the used nuclear fuel can be safely stored with utmost security and safeguarding of public health and safety. The term Independent Storage Facility (“ISF”) is used to describe a safe and secure system for medium term use, such as a 300-year service life, that would avert the need for establishing a disposal site in the near future and preserve the prospect of future scientific developments to provide a productive use for the used fuel. Equally important, it is necessary to have a dry storage system that, by virtue of its inherent safety, wins the confidence and acceptance of the public.